Human civilisation has been causing changes in weather patterns - the climate - for the last 100 years at least. When we burn coal, oil and natural gas to heat our homes, power our cars or generate electricity that releases carbon dioxide gas (CO2). That gas then traps the sun's heat in the Earth's atmosphere, which is why it's called a greenhouse gas.
Another major greenhouse gas is methane, produced by millions of cattle on farms across the world.
Greenhouse gases exist naturally in the atmosphere, but as we produce more and more of them, the Earth is starting to get warmer. That is causing more dramatic weather like floods and violent winds, with devastating effects. It's also melting the polar ice-caps melt, which means sea levels are rising. Global warming creates a domino effect, affecting mankind, plants and animals.
Your lifestyle and climate change
What things do you do that add to the amount of carbon dioxide in the atmosphere? Find out by calculating your carbon footprint.
What can you do?
Plant a tree – Trees soak up carbon dioxide and so help reduce climate change. The billion tree campaign has planted one billion trees a year since 2006. The campaign is now run by the Plant-for-the-Planet children initiative, set up by schoolboy Felix Finkbeiner. Watch Felix address the UN.
Turn off your lights – At 8.30pm on 23 March you can show your concern about our planet by simply turning off your lights. Hundreds of millions will be doing the same all over the world during Earth Hour. And save energy whenever, wherever and however you can.
Educate the next generation – Teach your younger brothers and sisters about climate change and encourage them to make a difference with these interactive games.